I have a 91 Z28 with a 5.7 TPI,here is what all i know with my problem, i know the fans are suppose to automatically turn on around 220-230 roughly. mine do not turn on at all, except when i turn the a/c on, so on that note i know its a sensor. Can anyone help me by telling me what sensor it is that is bad and where exactly it is located on the engine?
I thank you for your replies before hand, thank you for your help.

 

mine was on the intake. next to the thermostat housing in my 91. but mine was a tbi.

 

check the coolant fan relay. Most likely on the firewall. Drivers side. There is probably a second one of the same number you can swap it out with up there.